Moloney murine leukemia virus variants with distinct p30 peptide maps are associated with different clinical types of leukemia

Mouse leukemias arising after neonatal inoculation of Moloney MuLV (M-MuLV) are of two main types. One is characterized by enlargement of spleen and lymph nodes, and has a normal diploid karyotype. Thymus enlargement is the most prominent feature of the second type, with or without spleen involvement. About half of the thymomas are trisomic with an extra chromosome 15. C-type viruses isolated from the two leukemia types differed with regard to their p30 peptide maps. The p30s isolated from the preleukemic tissues of a 4-weeks-old, neonatally MuLV-inoculated mouse were either of the 'thymic' or the 'splenic' type. These results suggest that the two virus types were already present in the original inoculum and had homed to different tissues. The peptide maps of the corresponding gp70 molecules showed no organ-related pattern: each virus isolate had a distinct gp70 profile.